FS#47 - start/restart buttons

If a user clicks multiple times on the start or restart buttons, it can generate multiple instances of the server leading to issues with players joining and/or crashes. Suggesting a check be put in place to check for a currently running process under the intended screen session name to prevent duplicate servers.

This is also in due partly to the use of screen -R to reattach to the screen. If bgp for some reason does not detect the current session, it will create a new one. I modified my local code to utilize screen -x to reattach to those processes. This throws an error if the session doesn't exist and allows me to start the server and/or investigate the issue.